Tool shield



April 18, 1961 E. F. PFAFR ET Al. 2,979,724

TOOL SHIELD Original Filed Nov. 12, 1954 2 Sheets-Sheet 1 v A V r 33 27 45 35 T In 41 47 111 NVENTORSI 36 28 ELMER F FFAFF BY ROBERT W. HENNING ATTORNEY April 18, 1961 E. F. PFAFF ETAL TOOL SHIELD 2 Sheets-Sheet 2 Original Filed Nov. 12, 1954 FIG-3 2 IIIIIIIIIIIII" IIIIIIIIIIIIIIIA' FIG-4 INVENTORSZ ELMER F. PFAFF ROBERT W. HENNING ATTORNEY United States Patent TOOL SHIELD Elmer F. Pfatf, Mantua, and Robert W. Henning, Rocky River, Ohio, assignors, by mesne assignments, to Olin Mathieson Chemical Corporation, a 'corporation of Virginia Original application Nov. 12, 1954, Ser. No. 468,358, now Patent No. 2,925,600, dated Feb. 23, 1960. Divided and this application Mar. 24, 1959, Ser. No. 804,560

4 Claims. cu-44.5

This invention relates to a fastener driver and more particularly to an explosive operated stud driving tool. This application is a division of co-pending application Serial No. 468,358, filed November 12, 1954, now Patent No. 2,925,600, granted February 23, 1960.

In the use of explosive operated tools of the type disclosed in US. Patent Nos. 1,365,869 and 1,365,870 for driving studs or pins into structural materials it is often desirable to install the studs into rounded cylindrical objects such as columns, rods, poles, and pipe, for example. In such installations it is not only difiicult to properly position the tool for projecting the fastener, but the operation of driving studs into these round structures creates an extremely hazardous situation. It will be appreciated that in installations of this type as compared to installations where stud' driving occurs squarely into substantially planar surfaces, there is a greater tendency for the fastener to ricochet and endanger those in the vicinity of the operator and that ricochetting of such olfangle fasteners is of greater concern than the flash and occasional flash swept particles which may accompany the driving operation. Heretofore available types of tools, including those with shields, pads or guards, have provided no improvement in this respect over the tool with an unguarded muzzle.

Therefore, one object of the invention is to provide an improvement in explosive operated fastener driving tools for enabling the setting of fasteners properly into cylindrical or other curvilinear surfaces of like nature.

Another object is the provision of a new self-aligning tool assuring on round surfaces controlled and safe operation of explosive actuated driving tools in all directions on such Work surfaces.

Another object is the provision of a new and improved tool with a muzzle structure which substantially eliminates the likelihood of a fastener escaping into free flight as a result of inability to center the tool with round work surfaces properly. 1

A still further object is to provide on suchtools a self-centering and aligning safety shield for receiving spall particles and the blast from the muzzle thereby protecting not only the tool operator but also protecting other workmen in the vicinity from ricocheting missiles.

Other objects and advantages will be evident from the description and the accompanying drawing of preferred embodiments of the invention in which:

Figure 1 is an elevational view partly in cross-section showing part of a driving tool in accordance with one embodiment of this invention;

Figure 2 is a plan view of the embodiment of Figure 1 taken on line IIII of Figure 1;

Figure 3 is a cross-sectional view taken on line IlIIII of Figure 2; and

Figure 4 is taken on IV-IV of Figure 2 omittingthe piece of Work 50.

In accordance with this invention the muzzle end of an explosive actuated stud driving tool is provided with a safety shield adapted to center itself on the surface of notched in accordance with this invention.

2,979,72 Patented Apr. 18, 1951 cylindrical parts and to substantially retain disrupted particles such as spall fragments and the like within the shield structure. The shield or muzzle guard pad of this. invention comprises a box-like structure opened at one side at which it is presented to the work and having peripheral notches which enable the shield and the tool associated with it to be aligned properly with the work surface. Specifically, the side walls of the shield are A V-notch at any suitable angle in each of a pair of opposing Walls is contemplated which will accommodate the rounded surfaces usually encountered. The shield or muzzle guard may be provided with a notch having a fiX6d angle or a variable angle. When cylindrical objects of relatively large diameter constitute the Work, the angle of the notch is preferably near but somewhat less than When cylindrical objects of small diameter constitute the work the notch is at a more acute angle. Although for a given angle of notch a considerable range of work diameters can be handled, the range can be extended by providing a shield in accordance with this invention having an adjustable V-notch. Furthermore, in accordance with a preferred form of the invention, it is contemplated that the open side of the shield structure adjacent the-notches be provided with enclosures in the form of plates or the like the better to retain disrupted and ricochetting materials.

The embodiment preferred is illustrated in connection with the muzzle portion of a tool-of the type disclosed in the copending application of Kopf, Henning and Marsh, Serial No. 355,034, filed May 14, 1953 now Patent No. 2,945,236, granted July 19, 1960, for explosively actuated tools. A tool of this type comprises an outer barrel tube or housing 1, mounted for movement on barrel 2 so that the housing may be pushed forward relative to the barrel 2 into operative relationship when the tool barrel muzzle is placed against the surface into which the stud is to be installed and the tool held firmly against such surface. This type of tool also includes a shield tube or sleeve 3 for mounting the shield and a barrel spring 4, which is a compression type of spring adapted to press against the inner flange of shield tube 3 so as to urge the tube and shield forwardly. The barrel is threaded at the muzzle and carries a thread cap 99 which serves to transmit the thrust of barrel spring 4 acting through sleeve 3 to the barrel 2 and also as an axial retainer for the shield or muzzle guard structure.

.In this embodiment as shown in Figures 1 and 2, the self-centering safety shield structure takes the form of a receptacle consisting in general of a rear safety plate 6, which is apertured at 20 to receive the tool barrel 2. At the aperture 20 the safety shield is adapted to be attached at the muzzle of the barrel tool coaxially in any suitable manner as by being fixed on shield tube 3 which is constrained axially to have limited movement between cap 99 and spring 4. Although the invention described in connection with this embodiment is adapted to be attached to this form of explosive driving tool, it is to be understood that the invention in its general concept is not limited to the structural details or the arrangement of parts of a tool since the invention is adapted to be used with various forms of explosive operated tools or the like.

In operation the tool, loaded with a fastener and an explosive charge, is placed into position for firing with the self-aligning shield structure of this invention in engagement with the cylindrical surface of a piece of work which is to provide support or which is to be supported with the aid of a fastener driven into the surface. As illustrated in Figure 1 part of the marginal portions of the side walls are'pressed against a piece of work taking the form of a circular cylindrical tube 50 which may be apipe or column only a part of which is shown. After the explosive operated tool is positioned by the operator at a desired point on the work 50 with the aid of locating marks as described in the aforementioned Patent No. 2,925,600 which may take the form of indentations (Figure 1) or of superficially applied indicia marks the operator then pushes the tool against the cylindrical surface of object 50 until cap 99 and parts of the marginal portions of notched sides or at the plates 48 and 49 are firmly in engagement with the cylindrical surface. This places the entire shield structure in proper alignment and centered position on the cylindrical surface of the work 59. Because of the structural relationship of the notched side walls, and the apertured rear plate 6, it will be evident to those skilled in the art that the barrel of the tool is positioned squarely to the tagential plane at the point of the surface of object 56 into which it is desired to drive a stud. In this position it will be noted that the shield structure of this invention engages a surface of the pipe, or column into which the stud is to be driven so as to not only protect the tool operator from any flying particles at the time of firing but also to position the tool at a desirable firing angle at which danger of a glancing shot is substantially eliminated. With the tool thus positioned and fully compressed against the target surface, it may be fired in safety.

In the embodiment of Figures l to 4 there is shown a form of the device of this invention having an adjustable notch angle which permits a single shield structure to be used in connection with a maximum range of diameters of cylindrical surfaces including sharply curved surfaces as well as gently curved surfaces. 'As in the previous embodiment there is a rear safety plate 6 carried on the front end of tube 3 and having an integral flange 55 about an aperture for passage of the barrel 2 of an explosive operated stud driving tool. At the muzzle of the barrel 2, there is mounted any suitable form of retainer cap 99. The side walls, however, are in this embodiment formed by a pair of movable yoke-shaped'opposingsectors 21 and 22 including arcuate side walls and lateral sections made of metal such as steel and adapted to be carried at the ends of their lateral sections pivotally by the plate 6 at the headed pins 23 and 24 fastened in any suitable manner as by means of threads in bosses 46 and 47 of plate 6. The inside of the shield structure is provided as in the preceding embodiment with a resilient heat-resistant lining 25 which is preferably of a somewhat heavier section attached to the rear plate 6 and slidably bearing against the interior surface of the sectors 21 and 22. Sectors 21 and 22 are provided with partial front cover plates 48 and 49 respectively.

The shield is further provided with additional elements for securing movement of the sectors in unison in order that the axis of the barrel will always lie in the plane of bi-section of the dihedral angle formed by the anterior marginal edges of. sectors 21 and 22. For this purpose plate 6 is provided with a pair of slotted extensions 26 and 27, sector 21 is provided with a pair of perforations or apertures 28 and 29 and in like manner sector 22 is provided with a pair of perforations 30 and 31. Extending between each of the apertures in sectors 21 and 22 and one or the other of the slots. and 41 in the extensions 26 and 27 respectively is one of the four links' 32, 33, 34 and 35. One end of each link is pivotally connected at aperforation while the other end of the link is both pivotally and slidably mounted with respect to one or the other elongated slot of extensions 26 and 27 by means of a suitable pin and manually releasable fastener arrangement hereinafter described.

The embodiment of Figures 3 and 4 may be described in greater detail as to its component parts.

Sector 21, which is adapted for arcuate movement, includes lateral sections 36 and 37 and the front cover plate 48; and likewise sector 22 includes lateral sections 38 and 39 and front cover plate 49. Each of the lateral sections is pierced at the convergent ends for pivotal connections with one or the other of the pins 23 and 24 by means of which sectors 21 and 22 are pivotally mounted on plate 6 in articulated relationship. The anterior edges of lateral sections 36 and 38 of sectors 21 and 22 respectively are adapted to form one of the variable V-notches while lateral sections 37 and 39 of sectors 21 and 22 respectively are adapted to form the other opposed V-notch. The space between sections 36 and 37 is partially enclosed by plate 48 and in like manner plate 49 partially encloses the space between sections 33 and 39.

Lateral sector 36 is provided with a perforation 28 at which pivotal connection is made with link 32 at the other end of which pivotal connection is made slidably with a slot 40 in extension 26 by means of pivot screw 44. Lateral sector 38 is formed with perforation 30 at which pivotal connection is made with link 34 which in turn is connected pivotally in slidable relationship with slot 40 of the extension 26 also by means of screw 44. In like manner at perforations 29 and 31 lateral sections 37 and 39 respectively are pivotally connected with links 33 and 35 respectively which links in turn are pivotally connected slidably in slot 41 of the extension 27 by means of screw 45. Extensions 26 and 27 with the elongated slots 40 and 41 respectively are disposed on plate 6 in perpendicular relationship with the plate 6,'adjacent vthe lateral sectors 36, 37, 38 and 39 so that the slots 40 and 41 extend in parallel relationship to the axis of the tool barrel and the shield tube or sleeve 3 the latter of which is mounted coaxially with the tool barrel. This arrangement of parts permits the sectors 21 and 22 to move arcuately in desired unison which movement presents the axis of the tool barrel always squarely to the work surface at any of the angles of the V-notch obtainable with this embodiment. 'Sectors 21 and 22 can be fixed at the will of the tool operator at any setting of the V-notched angle desired by means of a T-head pivot screw and knurled or wing nut arrangement such as pivot screw 44 and knurled head clamp nut 42 in slot 40 for connection with links 32 and 34 and such as pivot screw 45 and knurled head clamp nut 43 passing through slot 41 for connection with links 33 and 35. It is evident that the pivot screws 44 and 45 may be modified to serve merely to pivotally carry the end of the links in slidable relationship with respect to the slots 40 and 41 and that the pivot pins 23 and 24 instead may be provided with a clamping arrangement to hold the desired angular setting of the notches.

In this embodiment the resilient liner 25 may advantageously take the form shown in Figure 3 which includes forwardly extending side wall sections extending from the section of the pad 25 attached to plate 6 only partially to the edge section of and along the interior of sectors 21 and 22. This skirt portion of resilient pad 25 acts as a seal between sectors 21 and 22 and the plate 6, thereby minimizing flash which would be a source of considerable discomfort to the tool operator.

In operation, the clamping nuts 42 and 43 are first loosened to permit adjustment of the V-notch angle to a desired value suitable to an object such as 50 after which the nuts are tightened. to hold this angle as in the preceding'embodiment. Thereafter it is merely necessary to press the shield structure of this invention and the loaded explosive operated tool associated therewith against the curvilinear surface of object 50 into which explosive driven studs are to be forceably emplaced. This action allows the housing 1 to move forwardly with respect to the shield structure and barrel to further compress barrel spring 4 while the gas cap 99 is attached with screw threaded adjustability on the muzzle of barrel 2 is positioned to abut with the surface of the object 50 as described in connection with the tool of the aforementioned Patent No. 2,945,236.

Since many other embodiments of this invention may occur to those skilled in the art, it is to be understood the foregoing is intended by way of illustration of an embodiment now believed to be preferred and not as a limitation of the scope of the present invention except as set forth in the appended claims. For example, it will be understood that the rear plate 6 of the shield may itself be folded to provide the dihedral angle which constitutes the V-notch set forth hereinbefore.

What we claim is:

1. A self-aligning shield structure for an explosively actuated stud driving tool comprising a rectangular rear plate apertured for passage of a tool barrel squarely therethrough, a pair of oppositely disposed yoke-shaped sectors pivotally mounted on a said plate so as to pivot about a line normal to the axis of the tool barrel, said sectors having lateral arcuate sections, said arcuate sections of one sector forming with the arcuate sections of the other sector oppositely disposed V-notches of substantially identical angles defining a dihedral angle the plane of bisection of which includes the axis of said tool barrel, and means for varying said V-notch angles in unison so as to preserve at any setting of the V-notch angles the geometrical relationship whereby the axis of the barrel of said tool is presented substantially squarely to the surface in centered relationship at the point of the surface at which a stud is to be explosively driven into the surface.

2. In an explosively operated stud driving tool having a barrel, said barrel having a muzzle end, said muzzle end being engageable with the cylindrical surface into which a stud is to be driven, a self-aligning safety shield structure mounted on said tool about the muzzle end of said barrel for engagement with said surface, said structure comprising a plate disposed transversely of said barrel, a pair of articulated members mounted pivotally on said plate for limited arcuate movement in unison about a plane including the axis of the bore of said barrel, said members having edges the intersection of which defines a forwardly facing dihedral angle bisected by said plane and front cover means carried by each of said members remotely from the line of intersection of said edges, said covers being spaced to form an opening through which the stud is drivable.

3. A self-aligning shield structure for an explosively actuated stud driving tool having a barrel, said barrel having a muzzle, said shield structure comprising a rear plate apertured for passage of said tool barrel at the muzzle substantially squarely therethrough in slidable relationship and having associated with the marginal portions thereof forwardly extending side walls forming with said rear plate a gas expansion missile confining chamber open at the front, said side walls including oppositely disposed members pivotally mounted and articulated with respect to each other by means of pivots to form substantially identical adjustable included marginal angles in spaced opposed relationship whereby the axis of the barrel of said tool may be presented substantially squarely to the curvilinear surface along a line including the point at which a stud is to be explosively driven when said shield structure is pressed into abutment with the surface at said marginal angles, said members 'being mounted on said rear plate for movement with respect thereto and with respect to each other about a common plane including said pivots and axis to adjust said included angles substantially equally to adapt said structure for abutment with variously curved surfaces.

4. The shield structure of claim 3 wherein the pivots are slidably mounted in slots extending substantially parallel with the axis and including means for releasably locking said. pivots and adjustably with respect to said slots to maintain the pivotally mounted members with their marginal angles at a desired adjustment.

No references cited. 

